( function () {
// Original src: https://github.com/zz85/threejs-path-flow
const BITS = 3;
const TEXTURE_WIDTH = 1024;
const TEXTURE_HEIGHT = 4;
/**
 * Make a new THREE.DataTexture to store the descriptions of the curves.
 *
 * @param { number } numberOfCurves the number of curves needed to be described by this texture.
 */

function initSplineTexture(numberOfCurves = 1) {
  const dataArray = new Float32Array(TEXTURE_WIDTH * TEXTURE_HEIGHT * numberOfCurves * BITS);
  const dataTexture = new THREE.DataTexture(dataArray, TEXTURE_WIDTH, TEXTURE_HEIGHT * numberOfCurves, THREE.RGBFormat, THREE.FloatType);
  dataTexture.wrapS = THREE.RepeatWrapping;
  dataTexture.wrapY = THREE.RepeatWrapping;
  dataTexture.magFilter = THREE.NearestFilter;
  dataTexture.needsUpdate = true;
  return dataTexture;
}
/**
 * Write the curve description to the data texture
 *
 * @param { THREE.DataTexture } texture The THREE.DataTexture to write to
 * @param { Curve } splineCurve The curve to describe
 * @param { number } offset Which curve slot to write to
 */

function updateSplineTexture(texture, splineCurve, offset = 0) {
  const numberOfPoints = Math.floor(TEXTURE_WIDTH * (TEXTURE_HEIGHT / 4));
  splineCurve.arcLengthDivisions = numberOfPoints / 2;
  splineCurve.updateArcLengths();
  const points = splineCurve.getSpacedPoints(numberOfPoints);
  const frenetFrames = splineCurve.computeFrenetFrames(numberOfPoints, true);

  for (let i = 0; i < numberOfPoints; i++) {
    const rowOffset = Math.floor(i / TEXTURE_WIDTH);
    const rowIndex = i % TEXTURE_WIDTH;
    let pt = points[i];
    setTextureValue(texture, rowIndex, pt.x, pt.y, pt.z, 0 + rowOffset + TEXTURE_HEIGHT * offset);
    pt = frenetFrames.tangents[i];
    setTextureValue(texture, rowIndex, pt.x, pt.y, pt.z, 1 + rowOffset + TEXTURE_HEIGHT * offset);
    pt = frenetFrames.normals[i];
    setTextureValue(texture, rowIndex, pt.x, pt.y, pt.z, 2 + rowOffset + TEXTURE_HEIGHT * offset);
    pt = frenetFrames.binormals[i];
    setTextureValue(texture, rowIndex, pt.x, pt.y, pt.z, 3 + rowOffset + TEXTURE_HEIGHT * offset);
  }

  texture.needsUpdate = true;
}

function setTextureValue(texture, index, x, y, z, o) {
  const image = texture.image;
  const {
    data
  } = image;
  const i = BITS * TEXTURE_WIDTH * o; // Row Offset

  data[index * BITS + i + 0] = x;
  data[index * BITS + i + 1] = y;
  data[index * BITS + i + 2] = z;
}
/**
 * Create a new set of uniforms for describing the curve modifier
 *
 * @param { THREE.DataTexture } Texture which holds the curve description
 */


function getUniforms(splineTexture) {
  const uniforms = {
    spineTexture: {
      value: splineTexture
    },
    pathOffset: {
      type: 'f',
      value: 0
    },
    // time of path curve
    pathSegment: {
      type: 'f',
      value: 1
    },
    // fractional length of path
    spineOffset: {
      type: 'f',
      value: 161
    },
    spineLength: {
      type: 'f',
      value: 400
    },
    flow: {
      type: 'i',
      value: 1
    }
  };
  return uniforms;
}
function modifyShader(material, uniforms, numberOfCurves = 1) {
  if (material.__ok) return;
  material.__ok = true;

  material.onBeforeCompile = shader => {
    if (shader.__modified) return;
    shader.__modified = true;
    Object.assign(shader.uniforms, uniforms);
    const vertexShader = `
		uniform sampler2D spineTexture;
		uniform float pathOffset;
		uniform float pathSegment;
		uniform float spineOffset;
		uniform float spineLength;
		uniform int flow;

		float textureLayers = ${TEXTURE_HEIGHT * numberOfCurves}.;
		float textureStacks = ${TEXTURE_HEIGHT / 4}.;

		${shader.vertexShader}
		` // chunk import moved in front of modified shader below
    .replace('#include <beginnormal_vertex>', '') // vec3 transformedNormal declaration overriden below
    .replace('#include <defaultnormal_vertex>', '') // vec3 transformed declaration overriden below
    .replace('#include <begin_vertex>', '') // shader override
    .replace(/void\s*main\s*\(\)\s*\{/, `
void main() {
#include <beginnormal_vertex>

vec4 worldPos = modelMatrix * vec4(position, 1.);

bool bend = flow > 0;
float xWeight = bend ? 0. : 1.;

#ifdef USE_INSTANCING
float pathOffsetFromInstanceMatrix = instanceMatrix[3][2];
float spineLengthFromInstanceMatrix = instanceMatrix[3][0];
float spinePortion = bend ? (worldPos.x + spineOffset) / spineLengthFromInstanceMatrix : 0.;
float mt = (spinePortion * pathSegment + pathOffset + pathOffsetFromInstanceMatrix)*textureStacks;
#else
float spinePortion = bend ? (worldPos.x + spineOffset) / spineLength : 0.;
float mt = (spinePortion * pathSegment + pathOffset)*textureStacks;
#endif

mt = mod(mt, textureStacks);
float rowOffset = floor(mt);

#ifdef USE_INSTANCING
rowOffset += instanceMatrix[3][1] * ${TEXTURE_HEIGHT}.;
#endif

vec3 spinePos = texture2D(spineTexture, vec2(mt, (0. + rowOffset + 0.5) / textureLayers)).xyz;
vec3 a =        texture2D(spineTexture, vec2(mt, (1. + rowOffset + 0.5) / textureLayers)).xyz;
vec3 b =        texture2D(spineTexture, vec2(mt, (2. + rowOffset + 0.5) / textureLayers)).xyz;
vec3 c =        texture2D(spineTexture, vec2(mt, (3. + rowOffset + 0.5) / textureLayers)).xyz;
mat3 basis = mat3(a, b, c);

vec3 transformed = basis
	* vec3(worldPos.x * xWeight, worldPos.y * 1., worldPos.z * 1.)
	+ spinePos;

vec3 transformedNormal = normalMatrix * (basis * objectNormal);
			`).replace('#include <project_vertex>', `vec4 mvPosition = modelViewMatrix * vec4( transformed, 1.0 );
				gl_Position = projectionMatrix * mvPosition;`);
    shader.vertexShader = vertexShader;
  };
}
/**
 * A helper class for making meshes bend aroudn curves
 */

class Flow {
  /**
   * @param {Mesh} mesh The mesh to clone and modify to bend around the curve
   * @param {number} numberOfCurves The amount of space that should preallocated for additional curves
   */
  constructor(mesh, numberOfCurves = 1) {
    const obj3D = mesh.clone();
    const splineTexure = initSplineTexture(numberOfCurves);
    const uniforms = getUniforms(splineTexure);
    obj3D.traverse(function (child) {
      if (child instanceof THREE.Mesh || child instanceof THREE.InstancedMesh) {
        child.material = child.material.clone();
        modifyShader(child.material, uniforms, numberOfCurves);
      }
    });
    this.curveArray = new Array(numberOfCurves);
    this.curveLengthArray = new Array(numberOfCurves);
    this.object3D = obj3D;
    this.splineTexure = splineTexure;
    this.uniforms = uniforms;
  }

  updateCurve(index, curve) {
    if (index >= this.curveArray.length) throw Error('Index out of range for Flow');
    const curveLength = curve.getLength();
    this.uniforms.spineLength.value = curveLength;
    this.curveLengthArray[index] = curveLength;
    this.curveArray[index] = curve;
    updateSplineTexture(this.splineTexure, curve, index);
  }

  moveAlongCurve(amount) {
    this.uniforms.pathOffset.value += amount;
  }

}
const matrix = new THREE.Matrix4();
/**
 * A helper class for creating instanced versions of flow, where the instances are placed on the curve.
 */

class InstancedFlow extends Flow {
  /**
   *
   * @param {number} count The number of instanced elements
   * @param {number} curveCount The number of curves to preallocate for
   * @param {Geometry} geometry The geometry to use for the instanced mesh
   * @param {Material} material The material to use for the instanced mesh
   */
  constructor(count, curveCount, geometry, material) {
    const mesh = new THREE.InstancedMesh(geometry, material, count);
    mesh.instanceMatrix.setUsage(THREE.DynamicDrawUsage);
    super(mesh, curveCount);
    this.offsets = new Array(count).fill(0);
    this.whichCurve = new Array(count).fill(0);
  }
  /**
   * The extra information about which curve and curve position is stored in the translation components of the matrix for the instanced objects
   * This writes that information to the matrix and marks it as needing update.
   *
   * @param {number} index of the instanced element to update
   */


  writeChanges(index) {
    matrix.makeTranslation(this.curveLengthArray[this.whichCurve[index]], this.whichCurve[index], this.offsets[index]);
    this.object3D.setMatrixAt(index, matrix);
    this.object3D.instanceMatrix.needsUpdate = true;
  }
  /**
   * Move an individual element along the curve by a specific amount
   *
   * @param {number} index Which element to update
   * @param {number} offset Move by how much
   */


  moveIndividualAlongCurve(index, offset) {
    this.offsets[index] += offset;
    this.writeChanges(index);
  }
  /**
   * Select which curve to use for an element
   *
   * @param {number} index the index of the instanced element to update
   * @param {number} curveNo the index of the curve it should use
   */


  setCurve(index, curveNo) {
    if (isNaN(curveNo)) throw Error('curve index being set is Not a Number (NaN)');
    this.whichCurve[index] = curveNo;
    this.writeChanges(index);
  }

}

THREE.Flow = Flow;
THREE.InstancedFlow = InstancedFlow;
THREE.getUniforms = getUniforms;
THREE.initSplineTexture = initSplineTexture;
THREE.modifyShader = modifyShader;
THREE.updateSplineTexture = updateSplineTexture;
} )();
